Polyurethane-gold and polyurethane-silver nanoparticles conjugates for efficient immobilization of maltogenase

Preparation of polyurethane microparticles (PU) modified with gold (Au-NPs) or silver nanoparticles (Ag-NPs) for maltogenase immobilization was presented. The PU/Au-NPs and PU/Ag-NPs conjugates were prepared via adsorption of already synthesized nanoparticles on PU or via synthesis of nanoparticles within bulk of PU. Au-NPs of different size and Ag-NPs, synthesized by reduction of tetrachloroauric acid and silver nitrate with sodium citrate, were characterized by UV-vis and Dynamic Light Scattering technique. The best results (immobilization yield 90.0% and efficiency 83.5%) were achieved, when maltogenase was immobilized onto PU modified with Au-NPs((13nm)) by adsorption method. Immobilized maltogenase was stable in time, after 25 days of storage 95.2-98.6% of initial enzyme activity was remained. Moreover, the results revealed that stability of enzyme was improved upon immobilization on PU/Au-NPs((13nm)) in comparison to PU without Au-NPs. Enhancement of photoluminescence after enzyme immobilization confirmed the successful attachment of maltogenase to PU/Au-NPs or PU/Ag-NPs via metal nanoparticles.